Falling film evaporator for power generation systems

ABSTRACT

A system ( 10 ) includes a condenser ( 12 ) with an inlet ( 22 ) and an outlet ( 24 ), a pump ( 14 ) with an outlet ( 28 ) and with an inlet ( 26 ) connected to the outlet ( 24 ) of the condenser ( 12 ), and an evaporator ( 16 ). The evaporator ( 16 ) includes an inlet ( 30 ) connected to the outlet ( 28 ) of the pump ( 14 ), an outlet ( 31 ), evaporating tubes ( 38 ), and a fluid distribution system ( 33 ) for spraying a fluid over the evaporating tubes ( 38 ). The system ( 10 ) further includes a turbine ( 18 ) with an inlet ( 44 ) connected to the outlet ( 31 ) of the evaporator ( 16 ), an outlet ( 48 ) connected to the inlet ( 22 ) of the condenser ( 12 ), and a drive shaft ( 46 ). A generator ( 20 ) is connected to the drive shaft ( 46 ) of the turbine ( 18 ).

CROSS-REFERENCE TO RELATED APPLICATION(S)

This application claims priority from U.S. Provisional Application No. 61/818,093, filed May 1, 2013 for “FALLING FILM EVAPORATOR FOR MIXED REFRIGERANTS” by Ahmad M. Mahmoud et al.

BACKGROUND

The present invention relates to power generation systems, and more specifically relates to a system with an evaporator for power generation systems.

The Organic Rankine Cycle (ORC) is commonly used as a power generation system for low temperature resources such as geothermal, solar thermal, biomass, and waste heat recovery. The primary components of an ORC system include an expansion device, a condenser, an evaporator/gas heater, and a motive pump. Traditionally Organic Rankine Cycle systems employ flooded evaporators, which use a shell and tube construction in order to evaporate a pool of liquid to produce superheated vapor. In typical flooded evaporators, a resource, such as hot water or hot fluid, flows through tubes. In less conventional systems, a hot gas flows through smoke tubes. The resource facilitates heat exchange between a pool of liquid, usually a working fluid comprised of a refrigerant, and the surface of the tubes to evaporate the liquid, resulting in superheated vapor. To continue the cycle, the superheated vapor exits the evaporator, expands in a turbine, spinning a generator, which then produces electricity. Low pressure and low temperature vapor exits the turbine and flows through a condenser where a cooler medium, such as air or water, condenses the vapor into liquid in a condenser. Liquid from the condenser is then pumped back into the pool of the flooded evaporator to repeat the cycle.

Flooded evaporators are disadvantageous for power generation cycles in terms of cost, environmental impact, footprint, and efficiency. Flooded evaporators require a significant amount of refrigerant charge to cover enough tubes to maintain sufficient heat transfer in order to evaporate the refrigerant liquid. In order to control the degree of superheat in order to maintain optimal turbine and system performance, a predetermined number of tubes remain unwetted in order to superheat the vapor being generated in the evaporator. The number of tubes that need to remain wetted is still quite significant, requiring a significant amount of refrigerant charge. Using a flooded evaporator, particularly for systems that utilize hydrofluorocarbons or other relevant working fluids, poses a significant cost concern due to the significant initial refrigerant charge, as well as the charge needed for maintenance and replenishment. Furthermore, due to thermal stratification effects and distribution of refrigerant, the refrigerant near the bottom of the evaporator requires a relatively higher temperature in order to evaporate the liquid thereby making the system less efficient.

SUMMARY

A system includes a condenser with an inlet and an outlet, a pump with an outlet and with an inlet connected to the outlet of the condenser, and an evaporator. The evaporator includes an inlet connected to the outlet of the pump, an outlet, evaporating tubes, and a fluid distribution system for spraying a fluid over the evaporating tubes. The system further includes a turbine with an inlet connected to the outlet of the evaporator, an outlet connected to the inlet of the condenser, and a drive shaft. A generator is connected to the drive shaft of the turbine.

In another embodiment, a method of processing a fluid includes condensing the fluid in a condenser, pumping the fluid from the condenser into an evaporator, and spraying the fluid from a fluid distribution system in the evaporator to cover evaporating tubes in the evaporator. The method further includes dripping an excess of the fluid off of the evaporating tubes to form a pool in the evaporator, evaporating the fluid from the evaporating tubes, expanding the evaporated fluid in a turbine, and producing power in a generator using the fluid expanded in the turbine.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a flow schematic of the present invention.

FIG. 2 is a flow schematic including an alternate embodiment evaporator of the present invention.

FIG. 3 is a cross section along line 3-3 in FIG. 2 of the alternate embodiment evaporator of the present invention.

FIG. 4 is a cross section along line 3-3 in FIG. 2 of another alternate embodiment evaporator of the present invention without superheating tubes.

FIG. 5 is a flow schematic including another alternate embodiment of the evaporator of the present invention with a recirculation pump and without pool boiling tubes.

FIG. 6 is a cross section along line 6-6 in FIG. 5 of another alternate embodiment evaporator of the present invention with a recirculation pump, without pool boiling tubes, and without super heating tubes.

DETAILED DESCRIPTION

The present invention utilizes a falling film evaporator to achieve efficient heat transfer in power generation systems, such as systems employing Organic Rankine Cycle (ORC) technology. The falling film evaporator of the present invention may include a falling film portion with evaporating tubes as well as a pool boiling portion with pool boiling tubes for evaporating excess refrigerant falling from the evaporating tubes. The falling film evaporator of the present invention may include a recirculation pump as an alternative to pool boiling tubes. The falling film evaporator of the present invention may also include a means for superheating to ensure optimal turbine and system performance. The falling film evaporator design reduces refrigerant charge necessity by 30%-70% as compared to a flooded evaporator. The falling film evaporator of the present invention enhances heat transfer, reduces cost, and reduces the size and footprint of state-of-the-art power generation systems.

The fluid employed in the falling film evaporator of the present invention may be a dry working fluid (not requiring superheat) or a wet working fluid (requiring superheat). The fluid may be a refrigerant, such as hydrofluorocarbons, hyrocarbons, fluorinated ketones, fluorinated ethers, chloro- and bromo-fluoro olefins, hydrofluoroolefins, hydrofluoroolefin ethers, hydrochlorofluoroolefin ethers, and linear and/or cyclic siloxanes. These compounds can be further defined as one or more of propane, cyclopropane, isobutene, isobutane, n-butane, propylene, n-pentane, isopentane, cyclopentane, R-134a, R-30, R-32, R-123, R-125, R-143a, R-134, R-152a, R-161, R-1216, R-227ea, R-245fa, R-245cb, R-236ea, R-236fa, R-365mfc, HT-55, R-43-10mee, HFE-7100, Novec-649, CF3I, R-1234 (ye and yf), R-1234ze, R-1233 (zd(E) and zd(Z)), R-1225 (ye(Z) and ye(E)), C5F9Cl, C5H2F10, R-1243zf, E-134a, E134, E125, E143a, siloxane MM, dimethylether, and CO2. Compounds may be selected based on characteristics that can enhance system performance, enhance heat transfer characteristics, provide fire suppression, provide flame retardation, provide lubrication, provide compound stabilization, provide corrosion inhibition, and provide solubility compatibility, tracing, prognostics or diagnostics.

FIG. 1 is a flow schematic of system 10 including condenser 12, pump 14, evaporator 16, turbine 18, and generator 20. Condenser 12 includes inlet 22 and outlet 24. Pump 14 includes inlet 26 and outlet 28. Evaporator 16 may be a falling film evaporator and consists of a shell through which superheating tubes 36, evaporating tubes 38, and pool boiling tubes 42 pass horizontally in tube bundles. Evaporator 16 also includes inlet 30, outlet 31, outlet 32, distribution system 33 with spray manifold 34 and spray nozzles 35, vapor lanes 37, and pool 40. Turbine 18 includes inlet 44 and outlet 48. Drive shaft 46 connects turbine 18 to generator 20.

System 10 may be an ORC system. System 10 processes a fluid to produce power. The fluid may be a wet working fluid, which requires superheat. The fluid enters evaporator 16 through inlet 30 using pump 14. Distribution system 33 uses spray nozzles 35 attached to spray manifold 34 to spray subcooled fluid at high pressure over evaporating tubes 38. Distribution system 33 is arranged in an overlaying relationship with the upper most level of the top of evaporating tubes 38. Evaporating tubes 38 consist of tube bundles which are positioned in a staggered manner under distribution system 33 to maximize contact with the fluid sprayed out of distribution system 33 onto the upper portion of evaporating tubes 38. To begin the evaporation process, the first row of evaporating tubes 38 is sprayed with subcooled fluid. Distribution system 33 is designed such that the first row of evaporating tubes 38 is drenched and covered but not oversupplied with fluid, starting the evaporation process. The fluid falls down subsequent rows of evaporating tubes 38. The fluid falling off the last row of evaporating tubes 38 collects and forms pool 40 at the bottom of evaporator 16. A control system may be employed to ensure that no dry-out occurs along the length and width of evaporating tubes 38.

In one embodiment, the fluid spray from distribution system 33 is controlled such that 15% of the fluid sprayed falls off the last row of evaporating tubes 38, while the rest of the fluid sprayed is evaporated by evaporating tubes 38. In an alternative embodiment, distribution system 33 is controlled such that 20% of the fluid sprayed falls off the last row of evaporating tubes 38. In another alternative embodiment distribution system 33 is controlled such that 25% of the fluid sprayed falls off the last row of evaporating tubes 38. In other embodiments, a control system is employed to vary the percentage of fluid falling off of the law row of evaporating tubes 38 between 5% and 50%.

Pool 40 covers pool boiling tubes 42. Pool boiling tubes 42 cause the fluid in pool 40 to evaporate. Therefore, the saturated vapor generated by evaporator 16 consists of fluid evaporated by evaporating tubes 38 and pool boiling tubes 42. Superheating tubes 36 are located on both sides of evaporating tubes 38. The saturated vapor travels along the periphery of evaporator 16 in vapor lanes 37, and when the saturated vapor reaches superheating tubes 36, superheating tubes 36 increase the temperature of the saturated vapor at a constant pressure, which results in favorable system performance. Since the fluid in system 10 may be a wet working fluid, superheating tubes 36 provide superheating to prevent liquid droplets from forming when the fluid expands through turbine 18. Superheating tubes 36 therefore ensure that the saturated vapor is heated sufficiently to result in favorable and proper performance of turbine 18.

Once the saturated vapor is superheated by superheating tubes 36, superheated vapor exits evaporator 16 through outlets 31 and 32 and superheated vapor enters turbine 18 through inlet 44. Turbine 18 expands superheated vapor spinning drive shaft 46, which drives generator 20 to produce power. Turbine 18 may be screw-shaped, axial, radial, or any other type of positive displacement shape. Low pressure and low temperature vapor from turbine 18 flows out through outlet 48 and into condenser 12 through inlet 22. In condenser 12, a cooler medium like air or water flowing through condenser 12 condensers the vapor into subcooled liquid. Subcooled liquid from condenser 12 exits through outlet 24 and enters pump 14 through inlet 26. Pump 14 pumps subcooled liquid through outlet 28 and into inlet 30 of evaporator 16. The cycle is subsequently repeated to continue to produce power.

FIG. 2 is a flow schematic of an alternative embodiment of the present invention, system 100, including condenser 112, pump 114, evaporator 116, turbine 118, and generator 120. Condenser 112 includes inlet 122 and outlet 124. Pump 114 includes inlet 126 and outlet 128. Evaporator 116 consists of a shell through which superheating tubes 136, evaporating tubes 138, and pool boiling tubes 142 pass in tube bundles. Evaporator 116 also includes inlet 130, outlet 132, distribution system 133 with spray manifold 134 and spray nozzles 135, vapor lanes 137, and pool 140. Turbine 118 includes inlet 144 and outlet 148. Drive shaft 146 connects turbine 118 to generator 120.

System 100 may be an ORC system. System 100 processes a fluid to produce power. The fluid may be a wet working fluid, which requires superheat. The fluid enters evaporator 116 through inlet 130 using pump 114. Distribution system 133 uses spray nozzles 135 attached to spray manifold 134 to spray subcooled fluid at high pressure over evaporating tubes 138. Distribution system 133 is arranged in an overlaying relationship with the upper most level of the top of evaporating tubes 138. Evaporating tubes 138 consist of tube bundles which are positioned in a staggered manner under distribution system 133 to maximize contact with the fluid sprayed out of distribution system 133 onto the upper portion of evaporating tubes 138. To begin the evaporation process, the first row of evaporating tubes 138 is sprayed with subcooled fluid. Distribution system 133 is designed such that the first row of evaporating tubes 138 is drenched and covered but not oversupplied with fluid, starting the evaporation process. The fluid falls down subsequent rows of evaporating tubes 138. The fluid falling off the last row of evaporating tubes 138 collects and forms pool 140 at the bottom of evaporator 116. A control system may be employed to ensure that no dry-out occurs along the length and width of evaporating tubes 138.

In one embodiment, the fluid spray from spray manifold 134 is controlled such that 15% of the fluid sprayed falls off the last row of evaporating tubes 138, and the rest of the fluid sprayed is evaporated by evaporating tubes 138. In an alternative embodiment, spray manifold 134 is controlled such that 20% of the fluid sprayed falls off the last row of evaporating tubes 138. In another alternative embodiment spray manifold 134 is controlled such that 25% of the fluid sprayed falls off the last row of evaporating tubes 138. In other embodiments, a control system is employed to vary the percentage of fluid falling off of the law row of evaporating tubes 138 between 5% and 50%.

Pool 140 covers pool boiling tubes 142. Pool boiling tubes 142 cause the fluid in pool 140 to evaporate. Therefore, the saturated vapor in evaporator 116 consists of fluid evaporated by evaporating tubes 138 and pool boiling tubes 142. Superheating tubes 136 are located above spray manifold 134. The saturated vapor travels along the periphery of evaporator 116 in vapor lanes 137, and when the saturated vapor reaches superheating tubes 136, superheating tubes 136 increase the temperature of the saturated vapor at a constant pressure, which results in favorable system performance. Since the fluid in system 100 may be a wet working fluid, superheating tubes 136 provide superheating to prevent liquid droplets from forming when the fluid expands through turbine 118. Superheating tubes 136 therefore ensure that the saturated vapor is heated sufficiently to result in favorable and proper performance of turbine 118.

Once the saturated vapor is superheated by superheating tubes 136, superheated vapor exits evaporator 116 through outlet 132 and superheated vapor enters turbine 118 through inlet 144. Turbine 118 expands superheated vapor spinning drive shaft 146, which drives generator 120 to produce power. Turbine 118 may be screw-shaped, axial, radial, or any other type of positive displacement shape. Low pressure and low temperature vapor from turbine 118 flows out through outlet 148 and into condenser 112 through inlet 122. In condenser 112, a cooler medium like air or water flowing through condenser 112 condensers the vapor into subcooled liquid. Subcooled liquid from condenser 112 exits through outlet 124 and enters pump 114 through inlet 126. Pump 114 pumps subcooled liquid through outlet 128 and into inlet 130 of evaporator 116. The cycle is subsequently repeated to continue to produce power.

FIG. 3 is a cross section of evaporator 116 of system 100 along line 3-3 in FIG. 2. Evaporator 116 consists of a shell through which superheating tubes 136, evaporating tubes 138, and pool boiling tubes 142 pass in tube bundles. Evaporator 116 also includes inlet 130, outlet 132, distribution system 133 with spray manifold 134 and spray nozzles 135, pool 140, resource inlet 152, resource inlet 154, resource outlet 156, and resource outlet 158.

Evaporator 116 is a two pass evaporator. During operation of evaporator 116, a resource, such as hot water, enters superheating tubes 136 through resource inlet 152, flows through superheating tubes 136 and into evaporating tubes 138 (as shown by the flow direction arrows), where the resource exits through resource outlet 156. The temperature of the resource is higher in superheating tubes 136 than in evaporating tubes 138. A resource, such as hot water, enters pool boiling tubes 142 through resource inlet 154, flows through pool boiling tubes 142 into evaporating tubes 138 (as shown by the flow direction arrows), where the resource exits through resource outlet 158. The temperature of the resource is higher in pool boiling tubes 142 than in evaporating tubes 138.

Subcooled liquid enters evaporator 116 through inlet 130. Distribution system 133 uses spray nozzles 135 attached to spray manifold 134 to spray subcooled fluid at high pressure over evaporating tubes 138. The heat from the resource flowing through evaporating tubes 138 allows the fluid to begin evaporating. The fluid falls down subsequent rows of evaporating tubes 138. The fluid falling off the last row of evaporating tubes 138 collects and forms pool 140 at the bottom of evaporator 116. The heat from the resource flowing through pool boiling tubes 142 causes the fluid in pool 140 to evaporate. Therefore, the saturated vapor in evaporator 116 consists of fluid evaporated by evaporating tubes 138 and pool boiling tubes 142. The saturated vapor travels up through evaporator 116, and when the saturated vapor reaches superheating tubes 136, the heat from the resource flowing through superheating tubes 136 increases the temperature of the saturated vapor at a constant pressure. Once the saturated vapor is superheated by superheating tubes 136, superheated vapor exits evaporator 116 through outlet 132.

FIG. 4 is a cross section of an alternative embodiment evaporator, evaporator 216, of system 100 along line 3-3 in FIG. 2. Evaporator 216 consists of a shell through which evaporating tubes 238 and pool boiling tubes 242 pass in tube bundles. Evaporator 116 also includes inlet 230, outlet 232, distribution system 233 with spray manifold 234 and spray nozzles 235, pool 240, resource inlet 252, resource inlet 254, resource outlet 256, and resource outlet 258. The fluid processed with evaporator 216 may be a dry working fluid, which does not require superheat. Therefore, evaporator 216 does not include superheating tubes.

During operation of evaporator 216, a resource, such as hot water, flows into evaporating tubes 238 through resource inlet 252. The resource continues to flow through additional evaporating tubes 238 (as shown by the flow direction arrows) and also flows into pool boiling tubes 242. The resource exits evaporating tubes 238 through resource outlet 256 and pool boiling tubes 242 through resource outlet 258.

Subcooled liquid enters evaporator 216 through inlet 230. Distribution system 233 uses spray nozzles 235 attached to spray manifold 234 to spray subcooled fluid at high pressure over evaporating tubes 238. The heat from the resource flowing through evaporating tubes 238 allows the fluid to begin evaporating. The fluid falls down subsequent rows of evaporating tubes 238. The fluid falling off the last row of evaporating tubes 238 collects and forms pool 240 at the bottom of evaporator 216. The heat from the resource flowing through pool boiling tubes 242 causes the fluid in pool 240 to evaporate. Therefore, the saturated vapor in evaporator 216 consists of fluid evaporated by evaporating tubes 238 and pool boiling tubes 242. The saturated vapor travels up through evaporator 216 and exits evaporator 216 through outlet 232.

FIG. 5 is a flow schematic including another alternate embodiment of the present invention, system 300, including condenser 312, pump 314, evaporator 316, turbine 318, generator 320, and recirculation pump 360. Condenser 312 includes inlet 322 and outlet 324. Pump 314 includes inlet 326 and outlet 328. Evaporator 316 consists of a shell through which superheating tubes 336 and evaporating tubes 338 pass in tube bundles. Evaporator 316 also includes inlet 330, outlet 332, distribution system 333 with spray manifold 334 and spray nozzles 335, vapor lanes 337, pool 340, and outlet 366. Recirculation pump 360 includes inlet 362 and outlet 364. Turbine 318 includes inlet 344 and outlet 348. Drive shaft 346 connects turbine 318 to generator 320.

System 300 may be an ORC system. System 100 processes a fluid to produce power. The fluid may be a wet working fluid, which requires superheat. The fluid enters evaporator 316 through inlet 330 using pump 314. Distribution system 333 uses spray nozzles 335 attached to spray manifold 334 to spray subcooled fluid at high pressure over evaporating tubes 338. Distribution system 333 is arranged in an overlaying relationship with the upper most level of the top of evaporating tubes 338. Evaporating tubes 338 consist of tube bundles which are positioned in a staggered manner under distribution system 333 to maximize contact with the fluid sprayed out of distribution system 333 onto the upper portion of evaporating tubes 338. To begin the evaporation process, the first row of evaporating tubes 338 is sprayed with subcooled fluid. Distribution system 333 is designed such that the first row of evaporating tubes 338 is drenched and covered but not oversupplied with fluid, starting the evaporation process. The fluid falls down subsequent rows of evaporating tubes 338. The fluid falling off the last row of evaporating tubes 338 collects and forms pool 340 at the bottom of evaporator 316. A control system may be employed to ensure that no dry-out occurs along the length and width of evaporating tubes 338.

In one embodiment, the fluid spray from spray manifold 334 is controlled such that 15% of the fluid sprayed falls off the last row of evaporating tubes 338, and the rest of the fluid sprayed is evaporated by evaporating tubes 338. In an alternative embodiment, spray manifold 334 is controlled such that 20% of the fluid sprayed falls off the last row of evaporating tubes 338. In another alternative embodiment spray manifold 334 is controlled such that 25% of the fluid sprayed falls off the last row of evaporating tubes 338. In other embodiments, a control system is employed to vary the percentage of fluid falling off of the law row of evaporating tubes 338 between 5% and 50%.

Recirculation pump 360 is an alternative to pool boiling tubes for evaporating pool 340. Recirculation pump 360 recirculates the fluid from pool 340 into inlet 330 of evaporator 316. The fluid in pool 340 exits evaporator 316 through outlet 364 and enters recirculation pump 360 through inlet 362. The fluid from pool 340 leaves recirculation pump 360 through outlet 364, merges with the fluid pumped from pump 314, and re-enters evaporator 316 through inlet 330. A control system may be employed to control the flow from recirculation pump 360 and the fluid flow from pump 314 in order to optimize distribution of liquid and minimize the amount of liquid pooling in pool 340.

The saturated vapor in evaporator 316 consists of fluid evaporated by evaporating tubes 338. Superheating tubes 336 are located above spray manifold 334. The saturated vapor travels along the periphery of evaporator 316 in vapor lanes 337, and when the saturated vapor reaches superheating tubes 336, superheating tubes 336 increase the temperature of the saturated vapor at a constant pressure, which results in favorable system performance. Since the fluid in system 300 may be a wet working fluid, superheating tubes 336 provide superheating to prevent liquid droplets from forming when the fluid expands through turbine 318. Superheating tubes 336 therefore ensure that the saturated vapor is heated sufficiently to result in favorable and proper performance of turbine 318.

Once the saturated vapor is superheated by superheating tubes 336, superheated vapor exits evaporator 316 through outlet 332 and superheated vapor enters turbine 318 through inlet 344. Turbine 18 expands superheated vapor spinning drive shaft 46, which drives generator 20 to produce power. Turbine 318 may be screw-shaped, axial, radial, or any other type of positive displacement shape. Low pressure and low temperature vapor from turbine 318 flows out through outlet 338 and into condenser 312 through inlet 322. In condenser 312, a cooler medium like air or water flowing through condenser 312 condensers the vapor into subcooled liquid. Subcooled liquid from condenser 312 exits through outlet 324 and enters pump 314 through inlet 326. Pump 314 pumps subcooled liquid through outlet 328 and into inlet 330 of evaporator 316. The cycle is subsequently repeated to continue to produce power.

FIG. 6 is a cross section of an alternative embodiment evaporator, evaporator 416, of system 300 along line 6-6 in FIG. 5, along with recirculation pump 460. Evaporator 416 consists of a shell through which evaporating tubes 438 pass in tube bundles. Evaporator 416 also includes inlet 430, outlet 432, distribution system 433 with spray manifold 434 and spray nozzles 435, pool 440, resource inlet 452, resource outlet 456, and outlet 466. Recirculation pump 460 includes inlet 462 and outlet 464. The fluid processed with evaporator 416 may be a dry working fluid, which does not require superheat. Therefore, evaporator 416 does not include superheating tubes.

During operation of evaporator 416, a resource, such as hot water, flows into evaporating tubes 438 through resource inlet 452. The resource continues to flow through additional evaporating tubes 438 (as shown by the flow direction arrows). The resource exits evaporating tubes 438 through resource outlet 456. Subcooled liquid enters evaporator 416 through inlet 430. Distribution system 433 uses spray nozzles 435 attached to spray manifold 434 to spray subcooled fluid at high pressure over evaporating tubes 438. The heat from the resource flowing through evaporating tubes 438 allows the fluid to begin evaporating. The fluid falls down subsequent rows of evaporating tubes 438. The fluid falling off the last row of evaporating tubes 438 collects and forms pool 440 at the bottom of evaporator 416.

Recirculation pump 460 is an alternative to pool boiling tubes for evaporating pool 440. Recirculation pump 460 recirculates the fluid from pool 440 into inlet 430 of evaporator 416. The fluid in pool 440 exits evaporator 416 through outlet 464 and enters recirculation pump 460 through inlet 462. The fluid from pool 440 leaves recirculation pump 460 through outlet 464, and re-enters evaporator 416 through inlet 430. A control system may be employed to control the flow of fluid into evaporator through inlet 430 in order to optimize distribution of liquid and minimize the amount of liquid pooling in pool 340. The saturated vapor in evaporator 416 consists of fluid evaporated by evaporating tubes 438. The saturated vapor travels up through evaporator 416 and exits evaporator 416 through outlet 432.

Discussion of Possible Embodiments

A system according to an exemplary embodiment of this disclosure, among other possible things includes: a condenser with an inlet and an outlet, a pump with an outlet and with an inlet connected to the outlet of the condenser, and an evaporator. The evaporator includes an inlet connected to the outlet of the pump, an outlet, evaporating tubes, and a fluid distribution system for spraying a fluid over the evaporating tubes. The system further includes a turbine with an inlet connected to the outlet of the evaporator, an outlet connected to the inlet of the condenser, and a drive shaft. A generator is connected to the drive shaft of the turbine.

A further embodiment of the foregoing system, wherein the system is a power generation system.

A further embodiment of any of the foregoing systems, wherein the fluid is a refrigerant.

A further embodiment of any of the foregoing systems, wherein the refrigerant is a hydrofluorocarbon, hydrocarbon, fluorinated ketone, fluorinated ether, chloro-olefin, bromo-fluoro olefin, hydrofluoroolefin, hydrofluoroolefin ether, hydrochlorofluoroolefin ether, linear siloxane, or cyclic siloxane.

A further embodiment of any of the foregoing systems, wherein the refrigerant is propane, cyclopropane, isobutene, isobutane, n-butane, propylene, n-pentane, isopentane, cyclopentane, R-134a, R-30, R-32, R-123, R-125, R-143a, R-134, R-152a, R-161, R-1216, R-227ea, R-245fa, R-245cb, R-236ea, R-236fa, R-365mfc, HT-55, R-43-10mee, HFE-7100, Novec-649, CF3I, R-1234ye, R-1234yf, R-1234ze, R-1233zd(E), R-1233zd(Z), R-1225ye(Z), R-1225ye(E), C5F9Cl, C5H2F10, R-1243zf, E-134a, E134, E125, E143a, siloxane MM, dimethylether, or CO2.

A further embodiment of any of the foregoing systems, wherein the evaporator further comprises pool boiling tubes.

A further embodiment of any of the foregoing systems, wherein the evaporator further includes superheating tubes near the outlet of the evaporator for heating the fluid evaporated by the evaporating tubes and pool boiling tubes.

A further embodiment of any of the foregoing systems, wherein the superheating tubes are next to the plurality of evaporating tubes below the fluid distribution system.

A further embodiment of any of the foregoing systems, wherein the superheating tubes are above the fluid distribution system.

A further embodiment of any of the foregoing systems, and further comprising a recirculation pump for recirculating fluid from the evaporator to the inlet of the evaporator.

A further embodiment of any of the foregoing systems, wherein the evaporator further includes superheating tubes near the outlet of the evaporator for heating the fluid evaporated by the evaporating tubes and pool boiling tubes.

A further embodiment of any of the foregoing systems, wherein the superheating tubes are next to the plurality of evaporating tubes below the fluid distribution system.

A further embodiment of any of the foregoing systems, wherein the superheating tubes are above the fluid distribution system.

A method of processing a fluid in a system according to an exemplary embodiment of this disclosure; the method, among other possible things includes: condensing the fluid in a condenser, pumping the fluid from the condenser into an evaporator, and spraying the fluid from a fluid distribution system in the evaporator to cover evaporating tubes in the evaporator. The method further includes dripping an excess of the fluid off of the evaporating tubes to form a pool in the evaporator, evaporating the fluid from the evaporating tubes, expanding the evaporated fluid in a turbine, and producing power in a generator using the fluid expanded in the turbine.

A further embodiment of the foregoing method, wherein the refrigerant is a hydrofluorocarbon, hydrocarbon, fluorinated ketone, fluorinated ether, chloro-olefin, bromo-fluoro olefin, hydrofluoroolefin, hydrofluoroolefin ether, hydrochlorofluoroolefin ether, linear siloxane, or cyclic siloxane.

A further embodiment of any of the foregoing methods, wherein the refrigerant is propane, cyclopropane, isobutene, isobutane, n-butane, propylene, n-pentane, isopentane, cyclopentane, R-134a, R-30, R-32, R-123, R-125, R-143a, R-134, R-152a, R-161, R-1216, R-227ea, R-245fa, R-245cb, R-236ea, R-236fa, R-365mfc, HT-55, R-43-10mee, HFE-7100, Novec-649, CF3I, R-1234ye, R-1234yf, R-1234ze, R-1233zd(E), R-1233zd(Z), R-1225ye(Z), R-1225ye(E), C5F9Cl, C5H2F10, R-1243zf, E-134a, E134, E125, E143a, siloxane MM, dimethylether, or CO2.

A further embodiment of any of the foregoing methods, wherein evaporating the fluid further comprises evaporating the fluid from the pool with pool boiling tubes.

A further embodiment of any of the foregoing methods, and further comprising heating the evaporated fluid with superheating tubes prior to expanding the evaporated fluid in the turbine.

A further embodiment of any of the foregoing methods, and further comprising recirculating the fluid from the pool in the evaporator back to the fluid distribution system of the evaporator.

A further embodiment of any of the foregoing methods, and further comprising heating the evaporated fluid with superheating tubes prior to expanding the evaporated fluid in the turbine.

A further embodiment of any of the foregoing methods, wherein the excess of the fluid dripping off of the evaporating tubes comprises between 15 and 25 percents of the fluid sprayed from the fluid distribution system.

Although the present invention has been described with reference to preferred embodiments, workers skilled in the art will recognize that changes may be made in form and detail without departing from the spirit and scope of the invention. 

1. A system comprising: a condenser with an inlet and an outlet; a pump with an outlet and with an inlet connected to the outlet of the condenser; an evaporator comprising: an inlet connected to the outlet of the pump; an outlet; a plurality of evaporating tubes; and a fluid distribution system for spraying a fluid over the plurality of evaporating tubes; a turbine with an inlet connected to the outlet of the evaporator, an outlet connected to the inlet of the condenser, and a drive shaft; and a generator connected to the drive shaft of the turbine.
 2. The system of claim 1, wherein the system is a power generation system.
 3. The system of claim 1, wherein the fluid is a refrigerant.
 4. The system of claim 3, wherein the refrigerant is a hydrofluorocarbon, hydrocarbon, fluorinated ketone, fluorinated ether, chloro-olefin, bromo-fluoro olefin, hydrofluoroolefin, hydrofluoroolefin ether, hydrochlorofluoroolefin ether, linear siloxane, or cyclic siloxane.
 5. The system of claim 4, wherein the refrigerant is propane, cyclopropane, isobutene, isobutane, n-butane, propylene, n-pentane, isopentane, cyclopentane, R-134a, R-30, R-32, R-123, R-125, R-143a, R-134, R-152a, R-161, R-1216, R-227ea, R-245fa, R-245cb, R-236ea, R-236fa, R-365mfc, HT-55, R-43-10mee, HFE-7100, Novec-649, CF3I, R-1234ye, R-1234yf, R-1234ze, R-1233zd(E), R-1233zd(Z), R-1225ye(Z), R-1225ye(E), C5F9Cl, C5H2F10, R-1243zf, E-134a, E134, E125, E143a, siloxane MM, dimethylether, or CO2.
 6. The system of claim 1, wherein the evaporator further comprises pool boiling tubes.
 7. The system of claim 6, wherein the evaporator further comprises a plurality of superheating tubes near the outlet of the evaporator for heating the fluid evaporated by the plurality of evaporating tubes and the plurality of pool boiling tubes.
 8. The system of claim 7, wherein the plurality of superheating tubes is next to the plurality of evaporating tubes below the fluid distribution system.
 9. The system of claim 7, wherein the plurality of superheating tubes is above the fluid distribution system.
 10. The system of claim 1, and further comprising a recirculation pump for recirculating fluid from the evaporator to the inlet of the evaporator.
 11. The system of claim 10, wherein the evaporator further comprises a plurality of superheating tubes near the outlet of the evaporator for heating the fluid evaporated by the plurality of evaporating tubes and the plurality of pool boiling tubes.
 12. The system of claim 11, wherein the plurality of superheating tubes is next to the plurality of evaporating tubes below the fluid distribution system.
 13. The system of claim 12, wherein the plurality of superheating tubes is above the fluid distribution system.
 14. A method of processing a fluid in a system, the method comprising: condensing the fluid in a condenser; pumping the fluid from the condenser into an evaporator; spraying the fluid from a fluid distribution system in the evaporator to cover a plurality of evaporating tubes in the evaporator; dripping an excess of the fluid off of the plurality of evaporating tubes to form a pool in the evaporator; evaporating the fluid from the plurality of evaporating tubes; expanding the evaporated fluid in a turbine; and producing power in a generator using the fluid expanded in the turbine.
 15. The method of claim 14, wherein the fluid is a refrigerant.
 16. The method of claim 15, wherein the refrigerant is a hydrofluorocarbon, hydrocarbon, fluorinated ketone, fluorinated ether, chloro-olefin, bromo-fluoro olefin, hydrofluoroolefin, hydrofluoroolefin ether, hydrochlorofluoroolefin ether, linear siloxane, or cyclic siloxane.
 17. The method of claim 16, wherein the refrigerant is propane, cyclopropane, isobutene, isobutane, n-butane, propylene, n-pentane, isopentane, cyclopentane, R-134a, R-30, R-32, R-123, R-125, R-143a, R-134, R-152a, R-161, R-1216, R-227ea, R-245fa, R-245cb, R-236ea, R-236fa, R-365mfc, HT-55, R-43-10mee, HFE-7100, Novec-649, CF3I, R-1234ye, R-1234yf, R-1234ze, R-1233zd(E), R-1233zd(Z), R-1225ye(Z), R-1225ye(E), C5F9Cl, C5H2F10, R-1243zf, E-134a, E134, E125, E143a, siloxane MM, dimethylether, or CO2.
 18. The method of claim 14, wherein evaporating the fluid further comprises evaporating the fluid from the pool with a plurality of pool boiling tubes.
 19. The method of claim 18, and further comprising heating the evaporated fluid with a plurality of superheating tubes prior to expanding the evaporated fluid in the turbine.
 20. The method of claim 14, and further comprising recirculating the fluid from the pool in the evaporator back to the fluid distribution system of the evaporator.
 21. The method of claim 20, and further comprising heating the evaporated fluid with a plurality of superheating tubes prior to expanding the evaporated fluid in the turbine.
 22. The method of claim 14, wherein the excess of fluid dripping off of the plurality of evaporating tubes comprises between 15 and 25 percent of the fluid sprayed from the fluid distribution system. 